MEXICO CITY, Sept 3 (Reuters) - Mexico’s government on Wednesday unveiled the winning design for a new, futuristic, spider-shaped airport for the capital that will ease delays and boost capacity at a cost of 120 billion pesos ($9.17 bln) in public and private funding.

British architect Norman Foster and Fernando Romero, a son-in-law of Mexican tycoon Carlos Slim, showcased their winning, airy design in the form of an X with arching spans at the presidential palace.

The new six-runway project will be built next to the Benito Juarez International Airport on the eastern flank of Mexico City, where the government already owns land.

“This airport is the first of its kind in the world,” Foster said. “It doesn’t have a conventional roof, it doesn’t have vertical walls. It doesn’t have columns in the normal sense.”

He cited challenges that include frequent earthquakes and the fact that the capital lies on a lake bed.

Mexico’s government will finance the first stage of the new airport and aims to issue up to 30-year bonds to finance later stages, a senior project official said.

Federico Patino, financial director of the project, told reporters it would initially be financed from operating cash flow generated by Mexico City’s current airport, which totals around 8.3 billion pesos ($634 million) a year.

”The airport infrastructure cost is around $10 billion, and we are going to raise $6 billion in (financial) markets,“ Patino said. ”The strategy includes short and medium-term financing.

“Once we have an adequate base, we will in the longer term issue up to 30-year bonds,” he added.

The project follows an abortive bid to build a new airport near the chosen site under former President Vicente Fox. That effort met with violent protests in which demonstrators armed with machetes and Molotov cocktails took 19 officials hostage after the government initially offered locals around 70 cents per square meter for land. It was canceled in 2002.

Foster is one of the world’s most famous architects, and his practice, Foster + Partners, has designed dozens of high-profile projects around the world, including Beijing Airport and London’s Wembley Stadium.

His firm also designed a London office building later nicknamed “the Gherkin” for its rounded shape, which has become one of the city’s leading landmarks.

Romero is married to Soumaya Slim, a daughter of one of the world’s richest men, and is the head of FR-EE Fernando Romero Enterprise.